This invention relates to vehicle safety belts, and in particular to such safety belts as are provided with automatic winding devices activated by spring force.
Safety belts are often provided with winding devices to increase the convenience and comfort of using the belt. Such winding devices generally include a spring activating roller which winds the belt when the belt is not being used to avoid the undesired presence of an excessive number of loose safety belts around the inside of the vehicle. When a vehicle occupant applies the safety belt, the belt is unwound from the roller and inserted into a belt lock. The spring force of the roller causes the belt to be applied closely to the vehicle occupant and the roller is generally provided with a locking device which prevents unwinding of the roller when the belt is subjected to a sudden force such as occurs in a vehicle collision.
One problem associated with such prior art safety belts is that in order to provide complete and effective retraction of the safety belt when the belt is not being used, it is necessary to provide the winding device with a rather strong rolling spring. Because of the inherent design of this spring rolling device, the spring force applied on the belt is greatest when the belt is unwound and applied to a vehicle occupant. While the passenger is free to move about against the winding force of the spring, the constant pressure of the spring may result in discomfort to the vehicle occupant, particularly on a long trip.
The passenger discomfort may be reduced by providing a weaker spring force on the roller of the winding device and therefore reduced belt force against the vehicle occupant. This solution often results in insufficient spring force to provide effective safety belt retraction particularly after a period of usage.
It is therefore an object of the present invention to provide a vehicle safety belt apparatus with a spring activated winding device wherein winding forces applied to a vehicle occupant are reduced.
It is a further object of the invention to provide such a safety belt apparatus wherein the winding forces are sufficient to effectuate complete retraction of the safety belt.